The present invention refers to a dispenser of washing agents, in particular for dishwashing machines.
It is known that washing machines usually provide for a dispenser of washing agents, such as detergents and additives; the latter are typically represented, in the case of laundry washing machines, by softening aids, and in the case of dishwashers by rinse aids.
In the case of dishwashers, the dispensers usually have a plastic body, made of two separate pieces welded together; in its front part, the body defines a space for containing a washing agent, usually a detergent, the space being provided with a small closing door, be it of the pivoted or sliding type.
Within the body of the dispenser there is then provided a reservoir for a second liquid washing agent, typically a rinse aid; a suitable metering mechanism provides for the supply of the necessary rinse aid amount from the reservoir towards the washing tank of the machine; it has to be noted that, usually, the rinse aid amount contained in the reservoir is enough for carrying out several washing cycles.
To the rear part of the body, outside it, there are associated one or more electric actuators and one or more kinematic devices, in order that the activation of the actuator(s) causes the opening of the small door of the detergent container and, at a following moment of a washing cycle, the supply of a predetermined amount of rinse aid.
Dispensers of the cited type are usually fastened in in registration with an opening defined on the internal surface of the washing machine door, so that a substantial part of the dispenser body, comprising the electrical and mechanical parts, is embedded inside the door itself; the front part of the dispenser, namely the one having the small door of the detergent containing space and the supplying outlet for the rinse aid, lays outside the opening and the machine""s door, directly facing on the inside of the washing tank.
Of course, a gasket is provided between the door opening""s edge and the external side of the dispenser body, in order to avoid the anger of water leakage within the door itself, wherein components supplied with electrical voltage are located.
Dispensers for washing agents of the above type can be used also in laundry washing machines, particularly of the top loading type (see for example EP-A-0 628 651).
As already mentioned, the main body of the dispenser is formed in two separate pieces, each one of them obtained usually by means of thermoplastic molding, the two pieces being then welded together in a second time; this in order to allow the arrangement, inside the body, of functional parts, such as some components of the rinse aid measuring system and/or an electric sensor of the level of the rinse aid in the associated reservoir.
According to the prior art, the connecting point, or weld line, between the two pieces which constitute the dispenser body, is located in the part of the body intended to be inserted inside the opening of the door, and is enclosed in the latter.
The present invention is based on the acknowledgement of the technical problem that the weld points located on the dispenser body represent potentially critical areas of the known dispensers.
In fact it may happen that, as time passes, along the weld between the plastic parts, micro-openings arise, due for instance to the vibration during the machine operation, and/or the mechanical stresses acting on the dispenser during the movements of closing the machine door, and/or the internal pressure of the dispenser due to the expansion in temperature of the rinse aid, and/or other mechanical stresses acting on the device during transportation or manufacturing (as for instance fortuitous falls of the device in the manufacturing line).
It may therefore happen that the micro-openings arise in the rinse aid reservoir, causing leakage of the liquid towards the inside of the machine door; such a fact can cause malfunction or failure of the machine, if the leaking rinse aid, which is electrically conductive, comes into contact with electrical arts inside the door, such as the supply terminals of an actuator of the dispenser, or its electric sensor, or the programming device of the machine itself, which usually is also located inside the machine door.
Furthermore, the rinse aid usually used in dishwashing machines is capable of corroding or otherwise deteriorating some plastic materials, such as the covering of electrical cables and wires; taking account of this fact, a rinse aid leakage inside the door can cause short circuits and potentially dangerous situations for the machine user.
The present invention has the aim of avoiding the above mentioned risks associated with washing agents dispensing devices of the known type.
Further aims, characteristics and advantages of the present invention will be clear from the following detailed description and the attached drawings, which are given as an explanatory and non limiting example only, and wherein: